Windy Tutorial: What is the difference between the reference time and the update time

Each model has a different update and reference times and it could be confusing what connection does it have to actual update. Before we get to how often are the weather models updated and where to find the update/reference time on Windy, let's see what's the difference between the reference time and the update time.

1. Reference time

Reference time is the time when a model starts a new forecast block. The process consists of the following:

Initialisation - data are entered into the model, this creates Initial conditions (initialisation time) and then model starts calculating conditions.

Assimilation - normalisation on data and assembling data for computation.

Computation - calculating the future atmospheric rates of change in time increments.

Data extraction - extracting data into regular forecast intervals.

Data storage - data are stored and written in accessible format.

Data postprocessing - special postprocessing routines

For example model ECMWF has an update interval 12 hours, that means the first reference time will be 00:00:00Z (Zulu time) and second one 12:00:00Z.

2. Update time

Update time is time between the reference time and the actual update. The whole process of data computation takes approximately from 8 to 9 hours. For example the ECMWF model update times are 07:15:00Z and 19:15:00Z.

When and how often are the weather data updated?

The table below describes when and how often are the weather models updated. All times are in UTC.

Where to find the reference and the update time

While on desktop, to get the reference and the update time, just click the clock icon in bottom right corner of the screen. In app, you have to dig deeper into the menu. See the screenshots below.